A one-of-a-kind Patek Philippe watch sold for $31 million at a charity auction in Geneva, making it the most expensive wristwatch ever auctioned. The Patek was sold as part of the Only Watch auction held by Christie's on Saturday to benefit research on Duchenne muscular dystrophy. The Patek Philippe Grandmaster Chime reference 6300A-010 is the only one of its kind …
